About evaluation of vegetation changes on permanent sample areas in Järvselja protected compartment

The changes in tree layer saplings, shrub, field and moss layer in Järvselja Nature Reserve virgin forest compartment (JS226) were analysed on the ground of data collected in 1955, 1985, 1993 and 2012. Four forest stands (sub-compartments) were studied; in every stand one 4 × 4 m sample area was established: area A1 represented Hepatica nobilis and Anemone nemoralis dominanted spruce stand, area A3 – drained transitional mire pine forest, area A4 – Mercurialis perennis-rich spruce stand and area A5 – Hepatica nobilis and Anemone nemoralis dominanted aspen stand. The number of tree layer saplings and shrub layer stems, as well as their species content have changed largely in all sample areas, being a bit more stable only on area A1. In field layer the abundance of initial dominant species changed remarkably in all areas or were replaced by other species in the course of succession. Changes in moss layer were the most striking in drained transition mire forest (area A3), where Pleurozium schreberi, Sphagnum centrale and S. capillifolium dominating in 1955 were replaced by S. centrale in 1993. The experiment planning in the current study is regrettably insufficient: to study forest communities succession using only one 4 × 4 m sample area in every stand does not allow to gather representative data about the vegetation structure and its variation limits. Moreover, in that way it is not possible to separate the time-induced successional trend from the drainage impact that has an obviously prevailing importance in forest compartment JS226 being surrounded by ditches.